Elastic strip of keyboard and method for producing the same

ABSTRACT

Elastic strips of a keyboard and a method for producing the same. An elastic sheet is produced by using a mold, wherein the elastic sheet has a plurality of rows of elastic domes formed thereon. Then, the elastic sheet is cut into a plurality of elastic strips, each of which has only one row of elastic domes.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates in general to elastic strips of akeyboard and a method for producing the same.

[0003] 2. Description of the Related Art

[0004] Referring to FIG. 1, a conventional keyboard of a notebookincludes a plurality of key caps 11 (only one key cap is shown in thefigure), a plurality of cap supports 12 (only one cap support is shownin the figure), an elastic sheet 13, a circuit membrane assembly 14 anda foundation sheet 15.

[0005] The foundation sheet 15 is a metal sheet on which a plurality ofseats 151 and hooks 152 are formed by punching and pressing.

[0006] The circuit membrane assembly 14 includes three membrane layers,wherein a middle layer is sandwiched by two outer layers. On the outerlayers are provided circuits, while on the middle layer are providedholes. By this arrangement, an electric conduction between the twocircuits on the outer layers is induced when the outer layers arecompressed to contact each other through the holes of the middle layer.Furthermore, a plurality of through holes 141 are provided on thecircuit membrane assembly 14. That is, the through holes 141 penetratethe outer layers and the middle layer of the circuit membrane assembly14.

[0007] The elastic sheet 13 is made of rubber and is formed by using theInjection Molding Method. The elastic sheet 13 has a sheet-like body130, a plurality of elastic domes 131, connecting portions 133 andthrough holes 132, wherein the connecting portions 133 connect theelastic domes 131 and the sheet-like body 130. Further referring to FIG.2, the elastic dome 131 has a plunger 1311 inside.

[0008] The cap support 12 has a first linking bracket 121 and a secondlinking bracket 122. The shaft portions 1221 of the second linkingbracket 122 are inserted into the holes 1211 of the first linkingbracket 121 so that the first linking bracket 121 and the second linkingbracket 122 are hinged together. Such a structure is so called“scissors-type support structure” Furthermore, the first linking bracket121 has shaft rods 1212, 1213 and the second linking bracket 122 hasshaft rods 1222 on their corners.

[0009] Referring to FIG. 3, the key cap 11 has hook portions 111 andholding portions 112, 113 on its bottom surface.

[0010] Now, the way of assembling the conventional keyboard isdescribed. The circuit membrane assembly 14 and the elastic sheet 13 areput on the foundation sheet 15, with the seats 151 and hooks 152 of thefoundation sheet 15 sticking out through the through holes 141 of thecircuit membrane assembly 14 and the through holes 132 of the elasticsheet 13. The key cap 11 is mounted on the foundation sheet 15 via thecap support 12, wherein the shaft rods 1212 are inserted into the seats151 so that the first linking bracket 121 is rotatable with respect tothe foundation sheet 15, and the narrow portion 1223 of the secondlinking bracket 122 is hooked by the hook 152 of the foundation sheet 15so that the second linking bracket 122 is also rotatable with respect tothe foundation sheet 15. Furthermore, the shaft rods 1213 of the firstlinking bracket 121 are held by the hook portions 111, and the shaftrods 1222 of the second linking bracket 122 are held by the holdingportions 112, 113.

[0011] In operation, the user pushes down the key cap 11 so as tocompress the elastic dome 131. Then, the plunger 1311 of the elasticdome 131 pushes against the circuit membrane assembly 14 so that anelectric conduction is induced to send out a corresponding signal.

[0012] In manufacture, however, the elastic sheet 13 of the conventionalkeyboard of a notebook has the following flaws: (1) The elastic sheet 13is made of rubber and formed by the Injection Molding Method. Buildingthe mold for the elastic sheet 13 is expensive. In addition,manufacturers need to build new molds for elastic sheets with newspecifications because different kinds of keyboards are provided withdifferent elastic sheets. Therefore, the cost for manufacturingkeyboards is high. (2) A mold is built when a keyboard of a newspecification is developed. However, if the elastic sheet 13 produced byusing the mold has dimensions outside the tolerance, then the mold needsto be rebuilt. Then, the cost of developing the new keyboard is raised,the time for developing the new keyboard is elongated and the massproduction of the new keyboards is delayed. It is disadvantageous forcommercial competition. (3) The elastic sheet 13 has a plurality of rowsof elastic domes 131 formed thereon. The distances between the rows ofelastic domes 131 must comply with the distances between the key caps ofthe keyboard. Therefore, the materials connected between the rows ofelastic domes 131 can not be eliminated. In other words, the weight ofthe elastic sheet 13 and the material cost cannot be reduced. (4) Theuser pushes down the key caps while typing. Referring to FIG. 4, thestroke for the key cap 11 to contact the elastic sheet 13 is “L”. For aconventional keyboard, however, the stroke generally is not long enoughfor the user to feel comfortable in operation. Referring to FIGS. 5A and5B, a possible way to increase the stroke is to provide rectangulargrooves 134 around the plunger 131. However, this arrangement reducesthe thickness of the elastic sheet under the grooves to “H” so that theresistance of the mold cavity to the flow of the molten material isincreased. Then, filling the mold cavity at the positions correspondingto the elastic domes tends to be incomplete.

SUMMARY OF THE INVENTION

[0013] An object of the present invention is to provide a means thatsolves the above-mentioned problems.

[0014] In the present invention, an elastic sheet is produced by using amold, wherein the elastic sheet has a plurality of rows of elastic domesformed thereon. Then, the elastic sheet is cut into a plurality ofelastic strips, each of which has only one row of elastic domes. Then,the elastic strips are disposed on keyboards.

[0015] To develop keyboards with new specifications, common portions ofthe new keyboard can use molds with prevailing specifications. Thus,only the molds for the elastic strips of new specifications need to bedeveloped, and the cost for developing a new keyboard is thereforegreatly reduced.

[0016] It is understood that only the molds for the new specificationsneed to be developed. If the development fails, the influences are localrather than overall. The engineers can fix the mistakes very soon so asto mass-produce the new keyboards in time. The present invention isadvantageous for commercial competition.

[0017] In the present invention, the elastic sheets are cut into aplurality of elastic strips. Thus, the distances between the rows of theelastic domes on the elastic sheets do not need to comply with thedistances between the key caps of the keyboards. The materials connectedbetween the rows of elastic domes are reduced. And the material cost andthe weight of the keyboard are reduced.

[0018] In the present invention, recesses are provided on the elasticstrips and between the elastic domes to increase the stroke for the keycaps to contact the elastic strips. While filling the mold cavity, thearrangement of the recesses does increase the resistance to the flow ofmolten material. However, the molten material can bypass the arrangementof the recesses so that the whole mold cavity is filled with moltenmaterial.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings, wherein:

[0020]FIG. 1 is an exploded perspective diagram of a conventionalkeyboard of a notebook;

[0021]FIG. 2 is a sectional diagram of a plunger of the keyboard;

[0022]FIG. 3 is a bottom view of a key cap of the keyboard;

[0023]FIG. 4 shows a stroke “L” for the key cap to contact the elasticsheet;

[0024]FIG. 5A depicts grooves provided on the elastic sheet to increasethe stroke for the key cap;

[0025]FIG. 5B is a top view of FIG. 5A;

[0026] FIGS. 6A-6D depict the process of producing elastic strips of thepresent invention;

[0027]FIG. 7 shows the arrangement of the elastic strips of the presentinvention on a keyboard;

[0028]FIG. 8A depicts a mold for producing the elastic strips of thepresent invention;

[0029]FIG. 8B is a sectional view of FIG. 8A along line B-B;

[0030]FIG. 8C is a sectional view of FIG. 8A along line C-C;

[0031]FIG. 9A shows an elastic sheet with recesses provided betweenelastic domes in accordance with an embodiment of the present invention;

[0032]FIG. 9B is a local enlarged view of FIG. 9A, depicting the flow ofmolten material for filling the mold cavity;

[0033]FIG. 9C depicts an elastic strip of an embodiment of the presentinvention obtained from cutting the elastic sheet shown in FIG. 9A;

[0034]FIG. 9D depicts a section of a keyboard with the elastic stripshown in FIG. 9C disposed thereon;

[0035]FIG. 9E depicts a key cap with notches provided on its edges inaccordance with the present invention;

[0036]FIG. 9F depicts an elastic strip with recesses provided betweenelastic domes in accordance with another embodiment of the presentinvention; and

[0037]FIG. 9G depicts the arrangement of the elastic strip shown in FIG.9F on the keyboard.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0038] In the present invention, an elastic strip shown in FIG. 6Drather than the elastic sheet of the prior art is used for a keyboard.It is noted that the elastic strip has only one row of elastic domes231. There are three different ways to produce the elastic strip of thepresent invention: (1) As shown in FIG. 6A, an elastic sheet 23 having aplurality of rows of elastic domes 231 is formed by the InjectionMolding method. Then, the elastic sheet 23 is cut into a plurality ofpieces 23 a, 23 b, 23 c, 23 d . . . , as shown in FIG. 6B, wherein eachpiece has only one row of elastic domes 231. Then, as shown in FIGS. 6Cand 6D, the pieces 23 a, 23 b, 23 c, 23 d are cut into the elasticstrips of the present invention, wherein the areas marked by the obliquelines are the removed portions. (2) The elastic sheet 23 shown in FIG.6A is directly cut into the elastic strip of the present invention shownin FIG. 6D. (3) The pieces 23 a, 23 b, 23 c, 23 d shown in FIG. 6B areproduced directly by the Injection Molding Method and then cut into theelastic strips of the present invention shown in FIG. 6D.

[0039] The elastic strips of the present invention are disposed on theabove-mentioned circuit membrane assemblies 14. It is noted that thedimensions of the key caps on a keyboard are not always the same. Thus,the elastic domes corresponding to the key caps are spaced differentdistances apart for different elastic strips, as shown in FIG. 7, inwhich D₁≠D₂≠D₃≠ . . . . In other words, a plurality of elastic stripscoming from different elastic sheets, in which the distances between theelastic domes are mutually different, are disposed on a keyboard.

[0040] The present invention provides the following advantages:

[0041] (1) For the keyboards with various specifications, commonportions may use the elastic strips with prevailing specifications,while different portions may use the elastic strips with newspecifications. Since only the molds for the elastic strips of newspecifications need to be developed, the cost for developing a newkeyboard is greatly reduced. (2) It is understood that only the moldsfor the elastic strips of new specifications need to be developed. Ifthe development fails, the influences on the keyboards are local ratherthan overall. The engineers can fix the mistakes very soon so as tomass-produce the new keyboards in time. Therefore, the present inventionis advantageous for commercial competition. (3) In the presentinvention, the elastic sheets are cut into a plurality of elasticstrips. Then, the elastic strips are disposed on keyboards. Thus, thedistances between the rows of the elastic domes on the elastic sheets donot need to comply with the distances between the key caps of thekeyboards. The materials connected between the rows of elastic domes canbe reduced. Also, the material cost and the weight of the keyboards arereduced. (4) Referring back to FIG. 6C, in the present invention, thethickness of the cut portions 235 remains unchanged while the thicknessof the connecting portions 232 is reduced. The reason for reducing thethickness of the connecting portions 232 is to increase the stroke forthe key cap to contact the elastic strip. The reason for maintaining thethickness of the cut portions is to facilitate the flowing of moltenmaterials in the mold cavity. Now referring to FIGS. 8A-8C, the obliquelines mark the mold body of the present invention. Inside the mold bodyis the mold cavity which includes first spaces 41, second spaces 42 andthird spaces 43 communicating with one another. The cut portions 235,connecting portions 232 and elastic domes 231 of the elastic sheet 23 ofthe present invention are formed in the first spaces 41, second spaces42 and third spaces 43, respectively. It is understood that the secondspaces 42, in which the thin connecting portions are formed, are smallerthan the first spaces 41 in which the thick cut portions are formed. Theresistance to the flow of molten material in the small second spaces isgreat. Nevertheless, most molten material flows to the third spaces viathe large first spaces 41 so that the filling of the third spaces iscomplete. Alternatively, recesses 233 are provided between the elasticdomes 231 as shown in FIG. 9A. The recesses 233 are used for receivingthe edges of the key caps so as to increase the stroke for the key caps.While filling the mold cavity, the arrangement of the recesses 233 doesincrease the resistance to the flow of molten material. However, themolten material can bypass the arrangement of the recesses 233 as shownin FIG. 9B, so that the whole mold cavity is filled with moltenmaterial. FIG. 9C depicts an elastic strip of another embodimentobtained from cutting the elastic sheet shown in FIG. 9A. FIG. 9Ddepicts a section of a keyboard with the elastic strip disposed thereon,wherein the recesses 233 are positioned under the edges of the key cap.Thus, the stroke for the key cap to contact the circuit membraneassembly is increased from “L” to “L+H”. Furthermore, as shown in FIG.9E, notches 115 are provided on the edges of the key cap for receivingthe connecting portions of the elastic strip when the key cap is pusheddown. By this arrangement, the stroke for the key cap is furtherincreased.

[0042] The above-mentioned recesses can be further modified to increasethe stroke for the key cap. As shown in FIG. 9F, the elastic strip isprovided with downward protrusions 236 to deepen the recesses 234.Further referring to FIG. 9G, through holes 143, 153 are provided on thecircuit membrane assembly 14 and the foundation sheet 15 for receivingthe protrusions 236. This arrangement increases the stroke for the keycap. Besides, disposing the elastic strip on the keyboard via thisarrangement is easy, fast and without deviations.

[0043] An important aspect of the present invention is changing theconventional elastic sheet into the elastic strips. Each elastic striphas only one row of elastic domes.

[0044] Furthermore, it is understood that the elastic strips of thepresent invention are suitable for various keyboards, besides thekeyboard provided with the “scissors-type support structure” mentionedabove.

[0045] While the invention has been described by way of example and interms of the preferred embodiment, it is to be understood that theinvention is not limited to the disclosed embodiments. To the contrary,it is intended to cover various modifications and similar arrangements(as would be apparent to those skilled in the art). Therefore, the scopeof the appended claims should be accorded the broadest interpretation soas to encompass all such modifications and similar arrangements.

What is claimed is:
 1. A method for producing elastic strips of akeyboard, including the steps of: (a) producing an elastic sheet byusing a mold, wherein the elastic sheet has a plurality of rows ofelastic domes; and (b) cutting the elastic sheet into the elasticstrips, each of which has only one row of elastic domes.
 2. A method forproducing elastic strips of a keyboard as claimed in claim 1, whereinrecesses are formed on the elastic sheet and between the elastic domesin step (a).
 3. A method for producing elastic strips of a keyboard,including the steps of: (a) producing an elastic sheet by using a mold,wherein the elastic sheet has a plurality of rows of elastic domes; (b)cutting the elastic sheet into a plurality of pieces, each of which hasonly one row of elastic domes; and (c) cutting the pieces into theelastic strips.
 4. A method for producing elastic strips of a keyboardas claimed in claim 3, wherein the pieces further have connectingportions connecting the elastic domes, and cut portions connecting theelastic domes and the connecting portions; wherein the cut portions arethicker than the connecting portions, and in step (c) the cut portionsare removed.
 5. A method for producing elastic strips of a keyboard,including the step of: (a) producing an elastic piece by using a mold,wherein the elastic piece has only one row of elastic domes.
 6. A methodfor producing elastic strips of a keyboard as claimed in claim 5,further including the step of (b) cutting the elastic piece into apredetermined shape.
 7. A method for producing elastic strips of akeyboard as claimed in claim 6, wherein the elastic piece has connectingportions connecting the elastic domes, and cut portions connecting theelastic domes and the connecting portions; wherein the cut portions arethicker than the connecting portions, and in step (b) the cut portionsare removed away.
 8. An elastic strip of a keyboard including only onerow of elastic domes.
 9. An elastic strip as claimed in claim 8, whereinrecesses are formed on the elastic strip and between the elastic domes.10. A keyboard, including: a foundation sheet; a circuit membraneassembly disposed on the foundation sheet; a plurality of elastic stripsdisposed on the circuit membrane assembly, each of the elastic stripshaving only one row of elastic domes; a plurality of cap supports; and aplurality of key caps movably mounted on the foundation sheet via thecap supports for pushing the elastic domes so that the elastic domespush against the circuit membrane assembly.
 11. A keyboard as claimed inclaim 10, wherein the elastic strips further have connecting portionsconnecting the elastic domes; and on the connecting portions are formedrecesses corresponding to edges of the key caps.
 12. A keyboard asclaimed in claim 10, wherein the elastic strips further have connectingportions connecting the elastic domes; and notches are provided on edgesof the key caps corresponding to the connecting portions.
 13. A keyboardas claimed in claim 10, wherein the elastic strips further havingconnecting portions connecting the elastic domes; recesses are formed onthe connecting portions corresponding to edges of the key caps; andnotches are provided on the edges of the key caps corresponding to therecesses.
 14. A keyboard as claimed in claim 10, wherein the elasticstrips further have protrusions facing the circuit membrane assembly,and first through holes are formed on the circuit membrane assembly toreceive the protrusions.
 15. A keyboard as claimed in claim 14, whereinsecond through holes are formed on the foundation sheet to receive theprotrusions.
 16. A method for producing an elastic strip of a keyboard,including the step of: (a) preparing a mold in which first spaces,second spaces smaller than the first spaces and third spaces areprovided and communicate with one another; (b) filling the mold withmolten material to form the elastic strip which has cut portions formedin the first spaces, connecting portions formed in the second spaces andelastic domes formed in the third spaces; and (c) removing the cutportions from the elastic strip.